A Design Methodology of Rope Tension Meter Used for Lift Automatic Door Assembly

The present work demonstrates a low-cost open-source design of a rope tension meter specifically designed for measuring rope tension of lift door assembly. The potential use of such an easy to use, economical and handy unit could be in a door operator production plant and on installation site for measuring rope tension. The rope tension meter consists of a sensor unit and the embedded system equipped with a signal conditioning circuit, digitization circuit, microcontroller, and interactive display. The sensor unit is designed such that the load cell is mounted on a custom-designed mechanical structure. The sensor unit can clip onto a rope using an attached hand screw. While measuring the rope tension, the sensor unit clipped on the rope gives an analog output signal proportional to the load applied on the load cell. The analog output signal of the load cell is fed to the microcontroller through the signal conditioning and digitization circuit, and the corresponding load value is displayed on a screen as per the desired units of the load. To evaluate whether the rope tension meter was working, tests were performed on an automatic door operator setup. In this test, the rope tension meter showed a proportional response for any changes in the tension and high repeatability in its results. To calibrate the rope tension meter signal against the rope tension in units of Newton [N], calibration tests were performed. The study described in this document tries to fill in the gap in the literature in regards to the development of rope tension meters used for measuring rope tension of lift automatic door assemblies. The design and the procedure discussed could be utilized by lift manufacturing and service companies for developing a portable and low-cost rope tension meter tool for factory or on-site use.